EVOLUTION OF THE HUMAN SPECIES 195 



fundamental results. While all men agree in the pos- 

 session of certain features which set them apart from 

 other members of the primate order, they differ among 

 themselves in such a way as to fall into four well-marked 

 subdivisions branching out from a common starting- 

 point. Furthermore, in each of these primary groups 

 the subordinate types arrange themselves also in the 

 manner of branches arising from a common limb. 

 This is the relation that we have earlier found to be a 

 universal one throughout the animal kingdom, and 

 science believes that it indicates everywhere an evolu- 

 tionary history — an actual development along dif- 

 ferent lines of descent of forms which have a common 

 starting-point and ancestry. 



The second principle is perhaps even more significant : 

 when we review the many races from the Caucasian to 

 the dwarf Negrito, we traverse a downward path which 

 will bring us inevitably to the higher apes. In our 

 survey of human races, we have passed from the Cau- 

 casian, with the largest brain and cranium and with 

 straight jaws well underneath the brain-case, to the 

 pygmy with a relatively small brain, with huge pro- 

 jecting jaws and with prominent ridges over the eyes; 

 one step more along that path would bring us to the 

 gorilla or the chimpanzee. The array of lower pri- 

 mates, from the lemur to the gorilla, gives a series of 

 forms exhibiting a progressive advance in respect to 

 the size of the brain and cranium, and a gradual retreat 

 of the jaws to a position underneath the cranium ; and 

 one step further brings us to man. In a word, these 

 two lines join — in fact, they are directly continuous. 

 There is a far smaller difference between the lowest man 



